A peace plan to end the conflict in eastern Ukraine came under renewed strain Wednesday, with Ukraine and Russia clashing publicly over the next steps and further Ukrainian military casualties from rebel attacks testing a fragile cease-fire.

Moscow reacted sharply after Ukraine agreed Tuesday to confer special status on rebel-controlled eastern regions and grant them limited self-rule — but only once local elections had been held under Ukrainian law, something unpalatable for rebel leaders who have proclaimed their own "people's republics.''

Russian Foreign Minister Sergei Lavrov said the Ukrainian parliament had sought to "rewrite'' the agreement reached in Minsk, Belarus, last month. Kremlin spokesman Dmitry Peskov said that "we are today further from realizing the Minsk agreement than we were a few days ago.''

In Kyiv, Prime Minister Arseny Yatseniuk responded that no one on the Ukrainian side had much optimism that Russia "and the terrorists'' would readily fulfill the Minsk plan.

"First and foremost: to comply with the Minsk agreement, the Russian bandits must clear out of the territory of Ukraine and give the possibility to Ukraine of carrying out honest and transparent elections in line with international standards,'' he said in televised comments at a government meeting.

Difference in strategies

The dispute, which could lead the deal into a dead-end, highlighted the different strategies toward the issue of self-rule in the east.

Kyiv is pushing a decentralization agenda in which it makes concessions aimed at blunting a drive for independence, while Moscow appears to be supporting a push by the rebels for powers that could give them veto over national policy and coming closer to officially recognizing the establishment of the two "people's republics'' in Ukraine's east.

Meanwhile, Kyiv's military said one Ukrainian soldier had been killed in rebel attacks in the past 24 hours and five had been wounded.

Fighting in a conflict in which more than 6,000 people have been killed has greatly diminished, although huge areas of Ukraine's industrialized east, including the big cities of Donetsk and Luhansk, are under rebel control.

Heavy military equipment has been withdrawn to put the opposing sides out of range of each other's big guns, in line with the Minsk agreement.

There is concern in Kyiv that Mariupol, a port city of 500,000 on the Sea of Azov that is still held by the government, could be a prime target for the Russian-backed rebels should the cease-fire collapse.

Steadfast on sanctions

In Washington, the White House said President Barack Obama and German Chancellor Angela Merkel in a phone call reiterated their agreement that there would be no easing of sanctions on Russia over its support for Ukrainian separatists until it had fulfilled all of its commitments under the Minsk agreement.

The White House said Vice President Joe Biden, who spoke separately with Poroshenko, welcomed Ukraine's move regarding special status for the rebel-controlled eastern regions.

Western governments, who are backing a $40 billion aid package for Ukraine over four years, regard the Minsk agreement as still the best opportunity for a lasting settlement.